1. Field of the Invention
The invention relates generally to energy storage and more specifically to an energy storage system using springs.
2. Background of the Invention
Existing methods of electrical power storage and generation used to provide alternative or backup power sources to established energy grid systems have various difficulties associated with them. These existing systems are often expensive, inefficient, have a limited lifetime and/or generation capacity. A continuing need exists for improvements in power storage and generation. Particularly, a continuing need exists to provide inexpensive and a long lasting renewable energy system.
The primarily method for storing energy for future use uses a chemical batteries to store charge. Chemical batteries are expensive and need to be replaced periodically. Alternatively, hydroelectric system using potential energy has been used to replace chemical batteries. For example, U.S. Pat. No. 7,656,050 titled “Hydroelectric pumped-storage” and issued Feb. 2, 2010, relates to storage of energy using aquifers. During a time a high demand, fluid flows under the influence of gravity from a first aquifer to a second aquifer, during which time the kinetic energy of the fluid is converted into electrical energy. During a time of low demand, fluid is moved (e.g., by turbine) from the second aquifer back to the first aquifer. Unfortunately, large amounts of fluid (thousands of acre feet) are needed to store a significant amount of energy. In U.S. Patent Publication No. 2006-0032374 titled “Hydraulic liquid pumping system” and published Feb. 16, 2006, a liquid pumping system utilizes liquid to compress a gas and uses a part of the compressed gas to recycle the liquid within the system. Unfortunately, as the gas is compress the gas heats up and without proper insulation the stored energy is lost through heat conduction. It is also difficult to convert the heat energy back into electrical energy. In U.S. Pat. No. 7,770,331 titled “Potential energy storage system” and issued Aug. 10, 2010, hydraulic support cylinders are arranged vertically below a building support columns and mounted on the foundation. Each cylinder is a reversible hydraulic turbine generator that generates electricity during peak demand. Fluid is allowed to discharge from the hydraulic support cylinders, through hydraulic turbine generator, into a reservoir. The building's weight thus provides potential energy on demand via the pressurized fluid. During off-peak hours, the hydraulic turbine generator is operated in reverse. Unfortunately using a building weight to pressurize the fluid is not portable and needs to be designed into the building making it cumbersome to use.
What is needed as an energy storage system that will be able store a greater amount of energy per volume and that will last for decades with nearly unlimited recharges with minimal maintenance.